Remember that time you and your friends tried to do the "Bloody Mary" chant into the bathroom mirror late at night and the only thing that scared you was your friend's dad screaming at you through the walls to "Go the &$@!% back to bed"?

Well, the new thing kids do today to scar themselves for life and possibly end up in therapy is the hashtag-driven "Charlie Charlie Challenge," which involves two pencils placed in the shape of a cross on a sheet of paper with two "yes" and two "no" answers written on opposite corners of the diagonal. A pencil is placed on one axis and the other balanced on top of it. Someone chants, "Charlie, Charlie, are you here?" and if the pencil moves, it means the players are in the presence of a Mexican demon.

But (dramatic pause)...are they?

A story in British newspaper The Independent Tuesday explained what's really making the pencils move when people chant, "Charlie, Charlie, are you here?" for a chance to ask further questions of the spirit world. It's just -- surprise -- a combination of gravity, friction and the position of the balanced pencil. The slightest vibration or wind movement can move the pencil in one direction because the precarious position of the top pencil and the lack of friction between the pencils makes it more likely to spin, according to the Independent story.

Related stories

Of course, the fact that the pencils appear to be moving by themselves makes this spooky game scarier than, say, the traditional Ouija board, since in that practice hands are touching the pointer. Also, according to the Internet-fueled urban legend, if participants fail to send Charlie back to the afterlife or close the portal that allowed them to summon the demon, Charlie will haunt them.

Some #charliecharliechallenge videos on social media (and there are many, serious and silly -- the demon-summoning practice scored its viral credentials by earning a hashtag on Twitter and Vine last week) feature other ghostly phenomena happening in the background. Participants can supposedly hear loud knocks on walls and various items falling of shelves as if an angry demon is acting out -- possibly because he's grown tired of being asked by teenage girls if Zayn Malik will ever join back up with One Direction. But that may have more to do with psychology than a psycho demon.

The researchers reported that 30 percent of subjects in their first test with the robot claimed to have felt an invisible presence touching them, and two people even asked to stop the experiment. The results of the study were published in the journal Current Biology.

Now playing:Watch this:
Ghost hunting tech: The Geiger Counter

0:45

So maybe it's just psychology that's making you believe there's a ghostly figure pushing that pencil or knocking a picture off the wall. It's just in your head, and before you freak out again, no, that doesn't mean there's a ghost living in your head.